Driving device used in sewing apparatus

ABSTRACT

A sewing apparatus includes a driving source, a second driven shaft, and an eccentric member of an eccentric mechanism. The second driven shaft is connected to a drive shaft of the driving source and rotates. The eccentric member is connected to the second driven shaft. The eccentric member is capable of converting the rotational motion of the second driven shaft into the up and down motion of sewing machine needles. A cushion member is disposed between the eccentric member and the second driven shaft.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2021-038707 filed on Mar. 10, 2021, thecontents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a driving device used in a sewingapparatus that includes an eccentric member for reciprocating a needleup and down and forms stitches on a workpiece.

Description of the Related Art

Conventionally, an instrument panel has been used in a vehicle interiorof an automobile. A skin material is sewn on the surface of theinstrument panel using a sewing apparatus. A sewing apparatus disclosedin JP 2004-065844 A includes a sewing machine unit and an eccentricmechanism. The sewing machine unit includes a needle for sewing the skinmaterial. The eccentric mechanism converts a rotational driving forcefrom a driving source into an up and down linear motion. The eccentricmechanism transmits the rotational driving force of the driving sourceto the sewing machine unit. The needle reciprocates up and down by theeccentric mechanism.

The eccentric mechanism includes an eccentric shaft, an eccentric, and aconnecting rod. The eccentric shaft is rotatably supported by a base.The eccentric shaft is rotated by the driving force from the drivingsource. The eccentric shaft is inserted through the eccentric. One endportion of the connecting rod is connected to the eccentric. The otherend portion of the connecting rod is connected to a slider. The slideris movable up and down.

The eccentric includes a bearing tube portion and an eccentric tubeportion. The bearing tube portion has a circular cross section. Athrough hole is provided in an axial center of the bearing tube portion.The eccentric tube portion has a circular cross section and is eccentricto the radially outer side of the bearing tube portion. The through holepenetrates from the bearing tube portion to the eccentric tube portion.By inserting the eccentric shaft into the through hole, the eccentricand the eccentric shaft rotate integrally. One end portion of theconnecting rod is rotatably supported on an outer peripheral side of theeccentric tube portion.

When the driving source is driven to rotate the eccentric shaft, theeccentric rotates together with the eccentric shaft. With the rotationof the eccentric, the connecting rod connected to the eccentric tubeportion reciprocates up and down. Thus, the up and down reciprocatingmotion of the connecting rod is transmitted to the slider. With thereciprocating motion of the slider, the needle of the sewing machineunit moves up and down via a connecting bar. As the needle moves up anddown, the skin material is sewn.

SUMMARY OF THE INVENTION

In the sewing apparatus described above, when the eccentric rotates andthe connecting rod reciprocates up and down, a load is applied to theeccentric tube portion from the connecting rod. The direction in whichthe load is applied is orthogonal to the axis of the eccentric shaft.Further, for example, when a workpiece made of a hard resin material issewn, a load is applied to the sewing machine unit in a directionopposite to a direction in which the needle is inserted into theworkpiece, as a reaction force caused by the insertion of the needleinto the workpiece. By applying these two types of loads, the eccentrictube portion is pressed radially inward. The eccentric tube portion isbent by the loads. Along with the deformation of the eccentric tubeportion, the eccentric tube portion and the outer peripheral surface ofthe eccentric shaft come into contact with each other and wear occurs.As a result, the durability of the sewing apparatus is reduced due towear.

An object of the present invention is to solve the above-describedproblems.

According to an aspect of the present invention, there is provided adriving device that is used in a sewing apparatus for sewing aworkpiece, and that drives a needle, the driving device comprising: adriving source configured to be driven to rotate when energized; a shaftconnected to the driving source and configured to rotate; and aneccentric member fixed to the shaft and configured to convert arotational motion of the shaft into an up and down motion of the needle,wherein a cushion member configured to absorb a load applied to theeccentric member in a direction substantially orthogonal to an axialdirection of the shaft is disposed between the eccentric member and theshaft.

According to the present invention, the driving device used in thesewing apparatus comprises the eccentric member. As a result, when thedriving source is driven to rotate the shaft, the rotational motion ofthe shaft is converted into the up and down motion of the needle by theeccentric member. At this time, a load in a direction substantiallyorthogonal to the axial direction of the shaft is applied to theeccentric member. The cushion member is disposed between the eccentricmember and the shaft. Thus, the load can be suitably absorbed by thecushion member.

As a result, when the eccentric member is pressed toward the shaftduring up and down movement of the needle, it is possible to reliablyprevent the eccentric member and the shaft from contacting each other bythe cushion member. Therefore, wear of the eccentric member issuppressed, and the durability of the sewing apparatus can be improved.

The above and other objects, features, and advantages of the presentinvention will become more apparent from the following description whentaken in conjunction with the accompanying drawings, in which apreferred embodiment of the present invention is shown by way ofillustrative example.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic configuration diagram showing a sewing mechanismof a sewing apparatus according to an embodiment of the presentinvention;

FIG. 2 is an enlarged front view showing one end side of a connectingrod and an eccentric member constituting the sewing mechanism of FIG. 1;

FIG. 3 is a cross-sectional view taken along line III-III of FIG. 2; and

FIGS. 4A, 4B, 4C, and 4D are diagrams illustrating the operation of theeccentric member shown in FIG. 2.

DESCRIPTION OF THE INVENTION

A sewing apparatus 10 sews a skin material 14 on the surface of aworkpiece 12 that is an object to be sewn. In the present embodiment,the workpiece 12 is an instrument panel mounted in a vehicle interior ofan automobile. The sewing apparatus 10 forms stitches along a sewingline (not shown) on the outer surface of the skin material 14 of theinstrument panel serving as the workpiece 12.

As shown in FIG. 1, the sewing apparatus 10 includes a casing 16, asewing mechanism 18, and a moving robot 20. The sewing mechanism 18 isattached to the casing 16. The sewing mechanism 18 functions as adriving device. The moving robot 20 is a moving mechanism that moves thesewing mechanism 18.

In the sewing apparatus 10, the sewing mechanism 18 and the moving robot20 are electrically connected to a control unit (not shown). The sewingmechanism 18 and the moving robot 20 are operated under the control ofthe control unit.

The sewing mechanism 18 is attached to a tip arm 22 of the moving robot20. In the sewing apparatus 10 shown in FIG. 1, an end on one side inthe width direction (an arrow B1 side) of the sewing apparatus 10 wherethe sewing mechanism 18 is disposed is referred to as a distal end. Anend on the other side in the width direction (an arrow B2 side) wherethe moving robot 20 is disposed is referred to as a proximal end.

The casing 16 has a U-shape that is open laterally in a side view seenfrom the width direction. The casing 16 is hollow. The casing 16includes a vertical frame portion 24, a lower frame portion 26, and anupper frame portion 28. The vertical frame portion 24 extends in avertical direction (directions of arrows A1 and A2). The lower frameportion 26 extends in the horizontal direction (directions of arrows B1and B2) from the lower end of the vertical frame portion 24. The upperframe portion 28 extends in the horizontal direction from the upper endof the vertical frame portion 24. The upper frame portion 28 and thelower frame portion 26 are separated from each other by a predetermineddistance in the vertical direction. The upper frame portion 28 and thelower frame portion 26 are parallel to each other.

The casing 16 includes a first protruding portion 30. The firstprotruding portion 30 is disposed at the distal end of the lower frameportion 26. The first protruding portion 30 protrudes upward (in anarrow A1 direction) from the lower frame portion 26 by a predeterminedheight. The distal end of the upper frame portion 28 includes a secondprotruding portion 32. The second protruding portion 32 is disposed toface the first protruding portion 30 in the vertical direction. Thesecond protruding portion 32 protrudes downward (in an arrow A2direction) from the upper frame portion 28 by a predetermined height.

In the casing 16, the inside of the first protruding portion 30, theinside of the lower frame portion 26, the inside of the vertical frameportion 24, the inside of the upper frame portion 28, and the inside ofthe second protruding portion 32 communicate with one another.

The sewing mechanism 18 includes a driving source 34, two sewing machineneedles (needles) 36 a and 36 b, a post bed 38, a first powertransmission mechanism 40, and a second power transmission mechanism 44.The post bed 38 is disposed so as to face the two sewing machine needles36 a and 36 b. The post bed 38 houses two loopers 42 a and 42 b. Thefirst power transmission mechanism 40 transmits the driving force of thedriving source 34 to the sewing machine needles 36 a and 36 b. Thesecond power transmission mechanism 44 transmits the driving force ofthe driving source 34 to the two loopers 42 a and 42 b.

The driving source 34 is, for example, a motor that is driven to rotatewhen energized. The driving source 34 includes a drive shaft 46 thatrotates. The driving source 34 is housed in the vicinity of the distalend in the upper frame portion 28. The drive shaft 46 of the drivingsource 34 is disposed to face the distal end of the upper frame portion28. The driving source 34 is disposed such that the drive shaft 46 ofthe driving source 34 extends horizontally. The distal end of the driveshaft 46 is connected, via a joint 48, to a first driven shaft 56(described later) of the first power transmission mechanism 40.

The sewing machine needles 36 a and 36 b extend in the verticaldirection (the directions of arrows A1 and A2). The sewing machineneedle 36 a and the sewing machine needle 36 b are disposed parallel toeach other while being separated from each other in the horizontaldirection (the directions of arrows B1 and B2). Upper ends of the sewingmachine needles 36 a and 36 b are held by a needle holder 50. The sewingmachine needles 36 a and 36 b protrude downward (in the arrow A2direction) from the lower surface of the needle holder 50. A sewingthread 52 a is inserted through a hole (not shown) of the sewing machineneedle 36 a. A sewing thread 52 b is inserted through a hole (not shown)of the sewing machine needle 36 b.

The needle holder 50 is disposed below the lower end of the secondprotruding portion 32. The needle holder 50 is connected to the lowerend of a reciprocating shaft 100 (described later) of the first powertransmission mechanism 40.

The post bed 38 is housed inside the first protruding portion 30. Thetwo loopers 42 a and 42 b and a part of the second power transmissionmechanism 44 are housed inside the post bed 38.

The loopers 42 a and 42 b are disposed in the vicinity of the upper endof the first protruding portion 30. The looper 42 a and the looper 42 bare disposed substantially parallel to each other while being separatedfrom each other in the horizontal direction. The loopers 42 a and 42 bare rotatably supported within the post bed 38 via a rotating shaft 54.Claw portions (not shown) protruding along the rotation direction arerespectively provided on outer peripheral portions of the loopers 42 aand 42 b. The looper 42 a is disposed below the sewing machine needle 36a. The looper 42 b is disposed below the sewing machine needle 36 b.

The loopers 42 a and 42 b are aligned with the sewing machine needles 36a and 36 b, respectively in the vertical direction. The loopers 42 a and42 b rotate with the claw portions taking the lead in the rotation. As aresult, tips of the sewing machine needles 36 a and 36 b are insertedfrom the outer surface toward the inner surface of the workpiece 12.When the tips of the sewing machine needles 36 a and 36 b protrude fromthe inner surface, the sewing threads 52 a and 52 b inserted through thesewing machine needles 36 a and 36 b are caught on the claw portions.

The first power transmission mechanism 40 is housed inside the upperframe portion 28 and the second protruding portion 32 in the casing 16.The first power transmission mechanism 40 includes the first drivenshaft 56, a second driven shaft (shaft) 60, and an eccentric mechanism62. The first driven shaft 56 is connected to the drive shaft 46 of thedriving source 34. The second driven shaft 60 is disposed in parallel tothe first driven shaft 56. The driving force is transmitted from thefirst driven shaft 56 to the second driven shaft 60 via a firsttransmission belt 58. The eccentric mechanism 62 is connected to thesecond driven shaft 60. The eccentric mechanism 62 transmits the drivingforce from the second driven shaft 60 to the sewing machine needles 36 aand 36 b.

Each of the first and second driven shafts 56 and 60 is formed from ametallic material. The first and second driven shafts 56 and 60 arehoused in the upper frame portion 28 of the casing 16. The first drivenshaft 56 is disposed in alignment with the drive shaft 46. The firstdriven shaft 56 is connected to the drive shaft 46 via the joint 48. Afirst pulley 64 is mounted to the distal end of the first driven shaft56.

The second driven shaft 60 is disposed below the first driven shaft 56(in the arrow A2 direction). The first driven shaft 56 and the seconddriven shaft 60 are separated from each other by a predetermineddistance in the vertical direction and substantially parallel to eachother. The second driven shaft 60 is elongated along the axial direction(the directions of arrows B1 and B2). The proximal end of the seconddriven shaft 60 extends to the vicinity of the proximal end of the upperframe portion 28.

A second pulley 66 is mounted to the distal end of the second drivenshaft 60. A third pulley 68 is mounted to the proximal end of the seconddriven shaft 60. An annular second transmission belt 70 is mounted onthe outer periphery of the third pulley 68.

The first transmission belt 58 has an annular shape having apredetermined width. The first transmission belt 58 is wound between thefirst pulley 64 and the second pulley 66. Thus, after the driving forceof the driving source 34 is transmitted to the first driven shaft 56,the driving force is transmitted to the second driven shaft 60 via thefirst pulley 64, the first transmission belt 58, and the second pulley66. As a result, the second driven shaft 60 rotates.

As shown in FIGS. 1 to 4D, the eccentric mechanism 62 includes aneccentric member 72, a connecting rod 74, a transmission shaft 76, and afixing screw (fixing member) 78. The eccentric member 72 is fixed to thesecond driven shaft 60. One end of the connecting rod 74 is connected tothe eccentric member 72. The other end of the connecting rod 74 isconnected to the transmission shaft 76. The fixing screw 78 is screwedinto the eccentric member 72.

As shown in FIGS. 2 to 4D, the eccentric member 72 includes a firstcylindrical portion 82 and a second cylindrical portion 84. The firstcylindrical portion 82 includes a shaft hole 80 penetrating through anaxial center L1 of the first cylindrical portion 82. The secondcylindrical portion 84 protrudes from the axial end face of the firstcylindrical portion 82 in the proximal end direction (in an arrow B2direction, toward one axial end side) along the axial direction of theshaft hole 80. The second cylindrical portion 84 is radially eccentricfrom the axial center L1 of the first cylindrical portion 82. Thecross-sectional shape of each of the first cylindrical portion 82 andthe second cylindrical portion 84 is circular when viewed from the axialdirection shown in FIG. 2.

The shaft hole 80 has a constant diameter and extends along the axialdirection (the directions of arrows B1 and B2). The second driven shaft60 can be inserted through the shaft hole 80. The shaft hole 80penetrates from the first cylindrical portion 82 to the secondcylindrical portion 84. The inner diameter of the shaft hole 80 islarger than the outer diameter of the second driven shaft 60. Aclearance C (see FIG. 3) is provided between the inner peripheralsurface of the shaft hole 80 and the outer peripheral surface of thesecond driven shaft 60. The clearance C has a predetermined width in theradial direction.

The shaft hole 80 includes a first hole portion 86 and a second holeportion 88. The first hole portion 86 is disposed inside the firstcylindrical portion 82. The second hole portion 88 is disposed insidethe second cylindrical portion 84. One end of the first hole portion 86opens at one axial end of the eccentric member 72 (an end on the distalend side, the arrow B1 side). One end of the second hole portion 88opens at the other axial end of the eccentric member 72 (an end on theproximal end side, the arrow B2 side). At this time, at one axial end ofthe eccentric member 72, the shaft hole 80 opens to the axial center L1of the first cylindrical portion 82. At the other axial end of theeccentric member 72, the shaft hole 80 opens at a position radiallyeccentric from an axial center L2 of the second cylindrical portion 84(see FIG. 2).

The second hole portion 88 includes an annular groove 90. The annulargroove 90 is disposed in the second hole portion 88 on the proximal endside (the arrow B2 side) of the eccentric member 72. The annular groove90 is recessed radially outward from the inner peripheral surface of thesecond hole portion 88. A ring-shaped cushion member 92 is mounted inthe annular groove 90.

The cushion member 92 is formed of an incompressible elastic material(incompressible material) such as rubber or silicone. The cushion member92 has an annular shape. The outer peripheral surface of the cushionmember 92 abuts against the inner peripheral surface of the annulargroove 90 and is held in the annular groove 90. The inner peripheralsurface of the cushion member 92 protrudes further inward in the radialdirection than the inner peripheral surface of the second hole portion88. The inner peripheral surface of the cushion member 92 is slidable onthe outer peripheral surface of the second driven shaft 60.

The cushion member 92 is not limited to being mounted to the eccentricmember 72. The cushion member 92 may be mounted to the outer peripheralsurface of the second driven shaft 60. The cushion member 92 is notlimited to being a single member and having an annular shape. Forexample, a plurality of the cushion members 92 may be scattered alongthe inner peripheral surface of the second hole portion 88.

The first cylindrical portion 82 includes a screw hole 94. As shown inFIG. 3, the screw hole 94 penetrates radially inward from the outerperipheral surface of the first cylindrical portion 82. The screw hole94 extends in the radial direction orthogonal to the shaft hole 80. Thescrew hole 94 penetrates from the outer peripheral surface of the firstcylindrical portion 82 to the shaft hole 80. The fixing screw 78 can bescrewed into the screw hole 94. The fixing screw 78 is a shaft having asubstantially constant diameter. The outer peripheral surface of thefixing screw 78 has threads. The fixing screw 78 is screwed into thescrew hole 94 from the outer peripheral surface of the first cylindricalportion 82. By screwing the fixing screw 78, the fixing screw 78 ismovable in the radial direction orthogonal to the axis of the shaft hole80.

After the second driven shaft 60 is inserted into the shaft hole 80 ofthe eccentric member 72, the fixing screw 78 is screwed. In accordancewith the screwing of the fixing screw 78, the fixing screw 78 is movedradially inward, that is, toward the second driven shaft 60. As aresult, the tip of the fixing screw 78 comes into contact with the outerperipheral surface of the second driven shaft 60. Therefore, theeccentric member 72 and the second driven shaft 60 do not rotaterelative to each other, and the eccentric member 72 and the seconddriven shaft 60 are fixed relative to each other. At this time, theclearance C is provided between the shaft hole 80 of the eccentricmember 72 and the second driven shaft 60. That is, the fixing screw 78is a fixing member that fixes the second driven shaft 60 and theeccentric member 72 without causing relative rotation therebetween.

As shown in FIGS. 1 to 4D, the connecting rod 74 extends in the verticaldirection (the directions of arrows A1 and A2). One end of theconnecting rod 74 in the longitudinal direction includes a first annularportion 96. The other end of the connecting rod 74 in the longitudinaldirection includes a second annular portion 98. Each of the first andsecond annular portions 96 and 98 has an annular shape. The firstannular portion 96 is disposed facing upward (in the arrow A1 direction)inside the second protruding portion 32. The second cylindrical portion84 of the eccentric member 72 is inserted into the first annular portion96. The second annular portion 98 is disposed facing downward (in thearrow A2 direction) inside the second protruding portion 32. Theproximal end of the transmission shaft 76 is inserted into the secondannular portion 98.

The first annular portion 96 is rotatably connected to the secondcylindrical portion 84 of the eccentric member 72. The second annularportion 98 is rotatably connected to the transmission shaft 76. Theconnecting rod 74 connects the second driven shaft 60 and thetransmission shaft 76. Thus, the connecting rod 74 can transmit thedriving force, which is transmitted to the second driven shaft 60, tothe transmission shaft 76.

As shown in FIG. 1, the transmission shaft 76 extends in the horizontaldirection (the directions of arrows B1 and B2) inside the secondprotruding portion 32. The proximal end of the transmission shaft 76 isrotatably supported by the second annular portion 98 of the connectingrod 74. The reciprocating shaft 100 is supported at the distal end ofthe transmission shaft 76. The reciprocating shaft 100 extends in thevertical direction (the directions of arrows A1 and A2) inside thesecond protruding portion 32. The needle holder 50 is mounted to thelower end of the reciprocating shaft 100.

The second power transmission mechanism 44 is housed inside the lowerframe portion 26 and the first protruding portion 30 in the casing 16.The second power transmission mechanism 44 includes a third driven shaft102. The third driven shaft 102 extends along the lower frame portion26. The third driven shaft 102 is separated from the second driven shaft60 in the vertical direction and is substantially parallel to the seconddriven shaft 60.

A fourth pulley 104 is connected to the proximal end of the third drivenshaft 102. A fifth pulley 106 is connected to the distal end of thethird driven shaft 102. The second transmission belt 70 is wound betweenthe fourth pulley 104 and the third pulley 68. Thus, the driving forceof the driving source 34 is transmitted to the second driven shaft 60 ofthe first power transmission mechanism 40, and is then transmitted tothe third driven shaft 102 via the third pulley 68, the secondtransmission belt 70, and the fourth pulley 104. As a result, the thirddriven shaft 102 rotates by the driving force of the driving source 34.

The second power transmission mechanism 44 includes a fourth drivenshaft 108, a third transmission belt 112, a first gear 114, and a secondgear 116. The fourth driven shaft 108 is disposed substantially parallelto the third driven shaft 102 inside the first protruding portion 30. Asixth pulley 110 is connected to the proximal end of the fourth drivenshaft 108. The third transmission belt 112 is wound around the fifthpulley 106 and the sixth pulley 110. The first gear 114 is fitted ontothe fourth driven shaft 108. The second gear 116 and the first gear 114mesh with each other.

The fourth driven shaft 108 is separated upward (in the arrow A1direction) from the third driven shaft 102 by a predetermined distance.The fourth driven shaft 108 is substantially parallel to the thirddriven shaft 102. The fourth driven shaft 108 is rotatably supported inthe first protruding portion 30.

The outer peripheral surface of the first gear 114 has a plurality offirst tooth portions (not shown) along the outer peripheral surface. Thefirst gear 114 is disposed at the axial center of the fourth drivenshaft 108. The first gear 114 is disposed adjacent to the sixth pulley110. The first gear 114 rotates together with the fourth driven shaft108.

The second gear 116 is connected to the axial center of the rotatingshaft 54. The rotating shaft 54 is disposed above the fourth drivenshaft 108. The rotating shaft 54 and the fourth driven shaft 108 areseparated from each other in the vertical direction and aresubstantially parallel to each other. The outer peripheral surface ofthe second gear 116 has a plurality of second tooth portions (not shown)along the outer peripheral surface. The second tooth portions of thesecond gear 116 and the first tooth portions of the first gear 114 meshwith each other. As a result, the first gear 114 and the second gear 116rotate together. The two loopers 42 a and 42 b are mounted to both endsof the rotating shaft 54 in the width direction so as to sandwich thesecond gear 116. The rotating shaft 54 rotates together with the secondgear 116, whereby the two loopers 42 a and 42 b rotate.

Next, the operation and effects of the sewing apparatus 10 will bedescribed.

First, the moving robot 20 is operated under the control of a controlunit (not shown). The tip arm 22 of the moving robot 20 is brought closeto the workpiece 12. Thus, the post bed 38 (loopers 42 a and 42 b) andthe sewing machine needles 36 a and 36 b are disposed at positionssandwiching the sewing line along which sewing is performed in theworkpiece 12. That is, the two loopers 42 a and 42 b and the two sewingmachine needles 36 a and 36 b are respectively disposed above and belowthe workpiece 12 (in the directions of arrows A1 and A2). Incidentally,the sewing threads 52 a and 52 b are passed through the holes (notshown) of the sewing machine needles 36 a and 36 b, respectively, inadvance.

Next, the driving source 34 is driven based on a control signal from thecontrol unit (not shown). The drive shaft 46 of the driving source 34rotates. The first driven shaft 56 and the first pulley 64 rotatetogether with the drive shaft 46. As the first pulley 64 rotates, thefirst transmission belt 58 revolves. As a result, the second pulley 66rotates via the first transmission belt 58, and the second driven shaft60 is driven to rotate together with the second pulley 66.

The eccentric member 72 rotates with the rotation of the second drivenshaft 60. The first cylindrical portion 82 of the eccentric member 72 isdisposed coaxially with the second driven shaft 60. Therefore, theeccentric member 72 rotates about the axial center L1 of the firstcylindrical portion 82. As shown in FIG. 2 and FIGS. 4A to 4D, thesecond cylindrical portion 84 of the eccentric member 72 turns at aposition eccentric radially outward from the second driven shaft 60. Forthis reason, the first annular portion 96 of the connecting rod 74 movestogether with the second cylindrical portion 84 along a substantiallyelliptical trajectory that turns at a position eccentric from the axialcenter L1 of the second driven shaft 60. In accordance with the movementof the first annular portion 96, the connecting rod 74 performs aturning motion while reciprocating up and down along a substantiallyelliptical trajectory.

At this time, as shown in FIG. 3, as the connecting rod 74 turns, a loadF is applied to the second cylindrical portion 84 of the eccentricmember 72 from the first annular portion 96 toward the second annularportion 98. The load F is applied by the gravity acting on theconnecting rod 74. When the load F is applied to the connecting rod 74,the second cylindrical portion 84 is pressed radially inward and isbent. The annular cushion member 92 made of an incompressible materialis disposed in the second hole portion 88 of the second cylindricalportion 84. Therefore, even if the second cylindrical portion 84 deformsand is bent radially inward, contact between the second cylindricalportion 84 and the second driven shaft 60 is reliably prevented by thecushion member 92.

Specifically, when the load F is applied from the first annular portion96 toward the second cylindrical portion 84, the distance by which thecushion member 92 pressed by the load F is compressed in the radialdirection is smaller than the radial length of the clearance C betweenthe inner peripheral surface of the first annular portion 96 (the secondhole portion 88) and the outer peripheral surface of the second drivenshaft 60. Therefore, even when the cushion member 92 is compressed inthe radial direction, the predetermined width of the clearance C ismaintained. In other words, when the cushion member 92 is compressed inthe radial direction, the width of the clearance C does not become 0.Thus, when the load F is applied from the first annular portion 96toward the second cylindrical portion 84, contact between the secondcylindrical portion 84 and the second driven shaft 60 is prevented bythe cushion member 92.

As shown in FIG. 1, the transmission shaft 76 is supported by the secondannular portion 98 of the connecting rod 74. Therefore, the transmissionshaft 76 performs a turning motion along a substantially ellipticaltrajectory similarly to the connecting rod 74. The reciprocating shaft100 reciprocates up and down once in synchronization with one turn ofthe transmission shaft 76. As the reciprocating shaft 100 reciprocates,the sewing machine needles 36 a and 36 b held by the needle holder 50also reciprocate up and down once.

The third pulley 68 rotates together with the second driven shaft 60.With the rotation of the third pulley 68, the second transmission belt70 revolves and the fourth pulley 104 rotates. With the rotation of thefourth pulley 104, the third driven shaft 102 is driven to rotate. Whenthe fifth pulley 106 rotates together with the third driven shaft 102,the third transmission belt 112 revolves.

As the third transmission belt 112 revolves, the sixth pulley 110, thefourth driven shaft 108, and the first gear 114 are driven to rotate. Asa result, the second gear 116 meshing with the first tooth portions ofthe first gear 114 is driven to rotate. With the rotation of the secondgear 116, the two loopers 42 a and 42 b fixed to the rotating shaft 54integrally rotate. Note that the two loopers 42 a and 42 b rotate insynchronization. While the two sewing machine needles 36 a and 36 breciprocate up and down once, the two loopers 42 a and 42 b rotate once.

The sewing machine needles 36 a and 36 b are inserted into the workpiece12 from the upper surface of the workpiece 12 by advancing along aforward path extending downward from the top dead center located at theuppermost position. When the sewing machine needles 36 a and 36 b reachthe bottom dead center located at the lowermost position, the tips ofthe sewing machine needles 36 a and 36 b protrude from the lower surfaceof the workpiece 12. The tips of the sewing machine needles 36 a and 36b protrude from the lower surface of the workpiece 12 and enter theinside of the post bed 38. As a result, the sewing threads 52 a and 52 binserted through the sewing machine needles 36 a and 36 b penetrate theworkpiece 12. Thereafter, the sewing machine needles 36 a and 36 badvance along a return path extending from the bottom dead center towardthe top dead center. While the sewing machine needles 36 a and 36 b arelifted, the sewing machine needles 36 a and 36 b are removed from thepost bed 38 and the workpiece 12.

When the sewing machine needles 36 a and 36 b are caused to penetratethe instrument panel serving as the workpiece 12 formed of a hard resinmaterial, a reaction force (load) directed upward is applied to thesewing machine needles 36 a and 36 b from the workpiece 12. Thisreaction force is transmitted from the sewing machine needles 36 a and36 b to the connecting rod 74 via the reciprocating shaft 100 and thetransmission shaft 76. As a result, the connecting rod 74 is biasedupward (in the arrow A1 direction) by the reaction force. Here, theannular cushion member 92 made of an incompressible material is mountedinside the second hole portion 88 of the second cylindrical portion 84of the eccentric member 72. Therefore, when a load is applied from thefirst annular portion 96 of the connecting rod 74 to the secondcylindrical portion 84 of the eccentric member 72, contact between thesecond cylindrical portion 84 and the second driven shaft 60 is reliablyprevented.

When the sewing threads 52 a and 52 b pass through the workpiece 12, theclaw portions (not shown) of the loopers 42 a and 42 b reach the topdead center. Then, when the loopers 42 a and 42 b rotate in a state inwhich the sewing threads 52 a and 52 b are caught on the claw portions,the sewing threads 52 a, 52 b is pulled downward. Thus, loop portionsare formed in the vicinity of the lower surface of the workpiece 12 bythe sewing threads 52 a and 52 b.

The sewing threads 52 a and 52 b pulled when the sewing machine needles36 a and 36 b are inserted (when the loopers 42 a and 42 b rotate) nexttime are inserted into the loop portions, respectively. The moving robot20 operates as appropriate under the control of the control unit. Withthe operation of the moving robot 20, the sewing mechanism 18 moves inparallel along the workpiece 12. In the sewing mechanism 18, the sewingmachine needles 36 a and 36 b reciprocate, and the loopers 42 a and 42 brepeatedly rotate. As a result, the plurality of loop portions arejoined to each other so that sewing is performed on the lower surface ofthe workpiece 12.

On the upper surface of the workpiece 12, stitches that are joinedlinearly are formed on the sewing line. As a result, the skin material14 is sewn on the upper surface of the workpiece 12.

In the present embodiment, the sewing apparatus 10 includes the sewingmechanism 18 for driving the two sewing machine needles 36 a and 36 b.The sewing mechanism 18 includes the driving source 34, the seconddriven shaft 60, and the eccentric member 72. The driving source 34 isdriven to rotate when energized. The second driven shaft 60 is connectedto the drive shaft 46 of the driving source 34 via the first drivenshaft 56 and rotates therewith. The eccentric member 72 is fixed to thesecond driven shaft 60. The eccentric member 72 converts the rotationalmotion of the second driven shaft 60 into the up and down motion of thesewing machine needles 36 a and 36 b. In the eccentric member 72, thecushion member 92 is disposed between the second driven shaft 60 and thesecond hole portion 88 into which the second driven shaft 60 isinserted.

The driving source 34 is driven to rotate the second driven shaft 60 andthe eccentric member 72. As the eccentric member 72 rotates, theconnecting rod 74 holding the sewing machine needles 36 a and 36 breciprocates up and down. At this time, the load F may be applied to theeccentric member 72, and the second cylindrical portion 84 may bepressed toward the second driven shaft 60 and deform. Even in the case,the cushion member 92 can prevent contact between the shaft hole 80 ofthe eccentric member 72 and the outer peripheral surface of the seconddriven shaft 60. As a result, wear (fretting) of the second driven shaft60 due to contact between the eccentric member 72 and the second drivenshaft 60 is suppressed. This makes it possible to improve the durabilityof the eccentric member 72 and the second driven shaft 60. By improvingthe durability of the eccentric member 72 and the second driven shaft60, it is possible to reduce the frequency of parts replacement andmaintenance man-hours for the eccentric member 72 and the second drivenshaft 60.

The eccentric member 72 includes the first cylindrical portion 82 andthe second cylindrical portion 84. The first cylindrical portion 82 isdisposed coaxially with the axial center L1 of the second driven shaft60. The second cylindrical portion 84 is disposed closer to the otherside in the axial direction of the second driven shaft 60 (the arrow B2side) than the first cylindrical portion 82 is. The axial center of thesecond cylindrical portion 84 is eccentric in the radial direction fromthe axial center L1 of the second driven shaft 60. The first annularportion 96 of the connecting rod 74 is connected to the secondcylindrical portion 84. The cushion member 92 is mounted to the secondcylindrical portion 84.

When the connecting rod 74 reciprocates up and down to reciprocate thesewing machine needles 36 a and 36 b up and down, the load F may beapplied from the first annular portion 96 to the second cylindricalportion 84. At this time, contact between the second cylindrical portion84 and the second driven shaft 60 is suitably prevented by the cushionmember 92, and wear of the second cylindrical portion 84 and the seconddriven shaft 60 can be avoided.

The second driven shaft 60 is inserted through the first cylindricalportion 82 and fixed to the first cylindrical portion 82 by the fixingscrew 78 in a direction orthogonal to the axial direction of the seconddriven shaft 60. Therefore, the eccentric member 72 and the seconddriven shaft 60 can be more firmly fixed by the fixing screw 78. As theeccentric member 72 and the second driven shaft 60 are fixed to eachother, contact between the eccentric member 72 and the second drivenshaft 60 is further suppressed, and wear can be reduced.

The annular cushion member 92 is mounted on the inner peripheral surfaceof the second hole portion 88 inside the second cylindrical portion 84.As a result, contact between the inner peripheral surface of the secondhole portion 88 and the second driven shaft 60 inserted through thesecond hole portion 88 can be reliably prevented by the cushion member92 over the entire circumferences of the second hole portion 88 and thesecond driven shaft 60.

The cushion member 92 is formed from an incompressible elastic materialsuch as rubber or silicone. Thus, when the load F is applied from thefirst annular portion 96 of the connecting rod 74 to the secondcylindrical portion 84 of the eccentric member 72, the load F can besuitably absorbed by the cushion member 92. For this reason, theclearance C between the second cylindrical portion 84 and the seconddriven shaft 60 can be constantly maintained by the cushion member 92.As a result, contact between the second cylindrical portion 84 and thesecond driven shaft 60 can be prevented.

The above embodiment can be summarized as follows.

The above embodiment relates to a driving device that is used in asewing apparatus (10) for sewing a workpiece, and that drives a needle(36 a, 36 b), the driving device comprising: a driving source (34)configured to be driven to rotate when energized; a shaft (60) connectedto the driving source and configured to rotate; and an eccentric member(72) fixed to the shaft and configured to convert a rotational motion ofthe shaft into an up and down motion of the needle, wherein a cushionmember (92) configured to absorb a load applied to the eccentric memberin a direction substantially orthogonal to an axial direction of theshaft is disposed between the eccentric member and the shaft.

According to this feature, when the needle reciprocates up and down asthe shaft and the eccentric member rotate, the load applied to theeccentric member can be absorbed by the cushion member. As a result,contact between the eccentric member and the shaft due to application ofthe load can be prevented by the cushion member. Therefore, thedurability of the eccentric member and the shaft can be improved.

The eccentric member includes: a first cylindrical portion (82) formedcoaxially with an axial center of the shaft; and a second cylindricalportion (84) disposed on one side of the first cylindrical portion inthe axial direction of the shaft, and radially eccentric from the axialcenter of the shaft, wherein the cushion member is disposed in thesecond cylindrical portion.

According to this feature, when the needle reciprocates up and down anda load is applied to the second cylindrical portion as the shaft and theeccentric member rotate, contact between the second cylindrical portionand the shaft is prevented by the cushion member. Therefore, wear of thesecond cylindrical portion and the shaft can be avoided.

The eccentric member and the shaft are fixed to each other by a fixingmember (78) provided in the first cylindrical portion. According to thisfeature, the eccentric member and the shaft can be firmly fixed by thefixing member. As a result, with the fixation of the eccentric memberand the shaft, contact between the eccentric member and the shaft isfurther suppressed, and wear of the eccentric member and the shaft canbe reduced.

Since the cushion member has an annular shape, contact between theeccentric member and the shaft can be reliably prevented over the entirecircumference of the shaft.

Since the cushion member is formed of an incompressible material, when aload is applied to the eccentric member, the load can be suitablyabsorbed by the cushion member. As a result, the clearance between theeccentric member and the shaft can be constantly maintained by thecushion member to prevent contact therebetween.

Note that the present invention is not limited to the embodimentdescribed above, and various configurations can be adopted thereinwithout departing from the gist of the present invention.

What is claimed is:
 1. A driving device that is used in a sewingapparatus for sewing a workpiece, and that drives a needle, the drivingdevice comprising: a driving source configured to be driven to rotatewhen energized; a shaft connected to the driving source and configuredto rotate; and an eccentric member fixed to the shaft and configured toconvert a rotational motion of the shaft into an up and down motion ofthe needle, wherein a cushion member configured to absorb a load appliedto the eccentric member in a direction substantially orthogonal to anaxial direction of the shaft is disposed between the eccentric memberand the shaft.
 2. The driving device according to claim 1, wherein theeccentric member includes: a first cylindrical portion formed coaxiallywith an axial center of the shaft; and a second cylindrical portiondisposed on one side of the first cylindrical portion in the axialdirection of the shaft, and radially eccentric from the axial center ofthe shaft, and the cushion member is disposed in the second cylindricalportion.
 3. The driving device according to claim 2, wherein theeccentric member and the shaft are fixed to each other by a fixingmember provided in the first cylindrical portion.
 4. The driving deviceaccording to claim 1, wherein the cushion member has an annular shape.5. The driving device according to claim 1, wherein the cushion memberis formed of an incompressible material.